From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F40FDC4167B for ; Fri, 3 Nov 2023 11:55:51 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qyslI-0004Ff-1s; Fri, 03 Nov 2023 07:54:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qyslH-0004FA-6U for qemu-devel@nongnu.org; Fri, 03 Nov 2023 07:54:51 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qyslC-0007Qj-Fd for qemu-devel@nongnu.org; Fri, 03 Nov 2023 07:54:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1699012483; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=p5P6rdhDQl3b3SrcXIzXcg6iSux+XwU+I8Q2XZYQjRg=; b=QcPfVrh3sjjDFO11gAnJlHjjM1mxd1NNOkRc4Rp4ih3iDKZcXaOF+c8D5f9wQWDE2MElhz /T+disxGN8H/g1SyKbTnjCdG0pxhliiH+s5NixlRDkDjbzt4/IrNeSKdLVAI6VVS7gyRLI j46DN1L0JzPhQmjgUdw4BeJT9Ktvzd4= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-403-FV0meGJoPriHqyI6QHYAiA-1; Fri, 03 Nov 2023 07:54:40 -0400 X-MC-Unique: FV0meGJoPriHqyI6QHYAiA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id BB3213C025BB; Fri, 3 Nov 2023 11:54:39 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DD0E65031; Fri, 3 Nov 2023 11:54:37 +0000 (UTC) Date: Fri, 3 Nov 2023 12:54:36 +0100 From: Kevin Wolf To: Markus Armbruster Cc: Vladimir Sementsov-Ogievskiy , Fiona Ebner , qemu-devel@nongnu.org, qemu-block@nongnu.org, eblake@redhat.com, hreitz@redhat.com, jsnow@redhat.com, den@virtuozzo.com, t.lamprecht@proxmox.com, alexander.ivanov@virtuozzo.com Subject: Re: [PATCH v2 00/10] mirror: allow switching from background to active mode Message-ID: References: <20231009094619.469668-1-f.ebner@proxmox.com> <993bfa5d-1a91-4b32-9bd8-165b7abba4f0@proxmox.com> <99dd287b-816b-4f4f-b156-32f94bbb62c2@yandex-team.ru> <87o7gbyy8w.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87o7gbyy8w.fsf@pond.sub.org> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.47, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Am 03.11.2023 um 10:36 hat Markus Armbruster geschrieben: > Vladimir Sementsov-Ogievskiy writes: > > > On 11.10.23 13:18, Fiona Ebner wrote: > >> Am 10.10.23 um 19:55 schrieb Vladimir Sementsov-Ogievskiy: > >>> On 09.10.23 12:46, Fiona Ebner wrote: > >>>> > >>>> Initially, I tried to go for a more general 'job-change' command, but > >>>> I couldn't figure out a way to avoid mutual inclusion between > >>>> block-core.json and job.json. > >>>> > >>> > >>> What is the problem with it? I still think that job-change would be better. > >>> > >> If going for job-change in job.json, the dependencies would be > >> job-change -> JobChangeOptions -> JobChangeOptionsMirror -> MirrorCopyMode > >> query-jobs -> JobInfo -> JobInfoMirror > >> and we can't include block-core.json in job.json, because an inclusion > >> loop gives a build error. > > Let me try to understand this. > > Command job-change needs its argument type JobChangeOptions. > > JobChangeOptions is a union, and JobChangeOptionsMirror is one of its > branches. > > JobChangeOptionsMirror needs MirrorCopyMode from block-core.json. > > block-core.json needs job.json for JobType and JobStatus. > > >> Could be made to work by moving MirrorCopyMode (and > >> JobChangeOptionsMirror, JobInfoMirror) to job.json or some place that > >> can be included by both job.json and block-core.json. Moving the > >> type-specific definitions to the general job.json didn't feel right to > >> me. Including another file with type-specific definitions in job.json > >> feels slightly less wrong, but still not quite right and I didn't want > >> to create a new file just for MirrorCopyMode (and > >> JobChangeOptionsMirror, JobInfoMirror). > >> And going further and moving all mirror-related things to a separate > >> file would require moving along things like NewImageMode with it or > >> create yet another file for such general things used by multiple block-jobs. > >> If preferred, I can try and go with some version of the above. > >> > > > > OK, I see the problem. Seems, that all requires some good refactoring. But that's a preexisting big work, and should not hold up your series. I'm OK to proceed with block-job-change. > > Saving ourselves some internal refactoring is a poor excuse for > undesirable external interfaces. I'm not sure how undesirable it is. We have block-job-* commands for pretty much every other operation, so it's only consistent to have block-job-change, too. Having job-change, too, might be nice in theory, but we don't have even a potential user for it at this point (i.e. a job type that isn't a block job, but for which changing options at runtime makes sense). > We need to answer two questions before we do that: > > 1. How much work would the refactoring be? > > 2. Is the interface improvement this enables worth the work? > > Let's start with 1. > > An obvious solution is to split JobType and JobStatus off job.json to > break the dependency of block-core.json on job.json. > > But I'd like us to investigate another one. block-core.json is *huge*. > It's almost a quarter of the entire QAPI schema. Can we spin out block > jobs into block-job.json? Moves the dependency on job.json from > block-core.json to block-job.json. It also makes job.json depend on block-job.json instead of block-core.json, so you only moved the problem without solving it. Kevin